docs: def delete_task(self, task_name):
          """ Deletes the named Task in this Job. """
  
          logger.debug('Deleting task {0}'.format(task_name))
          if not self.state.allow_change_graph:
              raise DagobahError("job's graph is immutable in its current state: %s"
                                 % self.state.status)
  
          if task_name not in self.tasks:
              raise DagobahError('task %s does not exist' % task_name)
  
          self.tasks.pop(task_name)
          self.delete_node(task_name)
          self.commit()